Create apps by using Microsoft Power Apps
Pick the app model first
Canvas apps fit when you need pixel-level control or a task-focused phone/tablet experience. Model-driven apps fit when data is already modelled in Dataverse and users need forms, views, charts and platform security. Power Pages fits external users. Exam questions frequently hide the app-type decision inside a scenario about offline use, custom branding, or external audiences.
In canvas apps, understand state scope. Global variables (Set) live for the session, context variables (UpdateContext) live on a screen, and collections (Collect/ClearCollect) hold tabular data that does not refresh automatically from the source. Use ThisItem inside a gallery and ThisRecord inside a form or function context - questions deliberately swap them.
Delegation is the most-tested trap. Any query the data source cannot translate is processed locally, silently returning only the first few hundred or thousand rows. Filters using StartsWith, exact equality on indexed columns, and date comparisons delegate to Dataverse; expressions that wrap the column in a function (for example Left(Name,3)="Con") do not.
Model-driven apps are assembled from a site map plus app components (forms, views, charts, dashboards) and are then published; security comes from Dataverse roles. Run the App Checker before shipping.
Worked example: a gallery must show accounts whose name begins with "Con" out of 50,000 records. Filter(Accounts, StartsWith(Name,"Con")) delegates; Filter(Accounts, Left(Name,3)="Con") does not and returns an incomplete list. Rule of thumb: if the function wraps the column instead of the value, expect a delegation warning.